GNOME 3

Summary

Owner

Current status

GNOME has been mostly updated to 2.91.6 in rawhide.
dconf, gtk3 and yelp-xsl and other new components are in rawhide.
The dbus a11y stack is now the default.
gtk3 modules have been added for at-spi2-atk, PackageKit and gtk-themes-standard.
The GNOME 3 visual appearance is being defined in the new theme packages gnome-icon-theme-symbolic and gnome-themes-standard.
The first Fedora15 GNOME3 test day has happened on Febuary 3.

Detailed Description

GNOME 3 is the next major version of the GNOME desktop. After many years of a largely unchanged GNOME 2.x experience, GNOME 3 brings a fresh look and feel with gnome-shell. There are also many changes under the surfaces, like the move from CORBA-based technologies such as GConf, Bonobo and at-spi to dbus-based successors.

The user experience of GNOME 3 is largely defined by gnome-shell, which is a compositing window manager and desktop shell. It replaces the GNOME 2 desktop shell, which consisted of metacity, gnome-panel, notification-daemon and nautilus.

Apart from pure window management, gnome-shell provides the top bar on the screen, which hosts the 'system status' area in the top right, a clock in the center, and a hot corner that switches to the so-called 'overview' mode, which provides easy access to applications and windows (and in the future, documents).

In gnome-shell, notifications are displayed in the 'messaging area' which is an automatically hiding bar at the bottom of the screen. This is also where integrated chat functionality is provided.

Since the requirements of gnome-shell on the graphics system may not be met by certain hardware / driver combinations, GNOME 3 also support as 'fallback mode' in which we run gnome-panel, metacity and notification-daemon instead of gnome-shell. Note that this mode is not a 'Classic GNOME' mode; the panel configuration will be adjusted to be similar to the shell.

The fallback will be handled automatically by gnome-session, which will detect insufficient graphics capabilities and run a different session.

Benefit to Fedora

Fedora stays in sync with upstream, and gains a modern user experience.
Some long-standing problems with the CORBA-based accessibility stack will hopefully be solved as a side-effect of the move to D-Bus

Upgrades need to ensure that all new components of GNOME 3 get installed when upgrading from an earlier Fedora release including GNOME 2.x. This includes in particular

gnome-shell (handled by a gnome-panel -> gnome-shell dependency now)

gnome-themes-standard

How To Test

How to test basic gnome-shell functionality:

Use a system with supported graphics card

Log in to a GNOME session

Verify that your desktop has:

A black panel at the top

Your name on the top right

Next to it, a system status area, with icons for sound, universal access, network, battery, etc, in symbolic style

in the center of the panel, a clock that brings up a calendar popup when clicked

on the left, an 'Activities' item that brings up the 'overview' when clicked

the top left corner of the screen also functions as a hot corner to bring up the overview

Notifications (ie 'bubbles') appear centered at the bottom of the screen, and are still available afterwards in the auto-hide 'messaging area' at the bottom right

How to test control-center functionality:

Log in to a GNOME session

Start the control-center by going to the user menu and selecting 'System Settings'

Verify that search functionality in the control-center works. E.g. typing 'batt' should find the Power panel (assuming English UI)

Test the functionality of various panels; settings should generally be immediate-apply, unless the panel has an 'Apply' button

Several panel offer privileged operations (such as creating user accounts or installing software). Verify that the PolicyKit integration for these works

How to test the accessibility stack:

Make sure at-spi2-core, at-spi2-atk, pyatspi are installed

Turn accessibility support on, with the command

gsettings set org.gnome.desktop.interface accessibility false

Log in again

Use the 'Universal access' menu in the system status area to turn various accessibility technologies on and off

Verify that accessibility technologies work as expected

Bring up the Universal Access settings, and make various changes

Verify that the changes take effect

How to test fallback:

Use a system with supported graphics card

Log in to a GNOME session

Verify that you end up with gnome-shell

Switch to a system with a graphics card on which we don't have 3d support (e.g. a VM)

Log in to a GNOME session again

Verify that you end up with the 'fallback' desktop

Repeat the same test with a supported graphics card, but uninstall gnome-shell. You should again get the 'fallback' desktop

How to test multi-monitor functionality:

Use a system with 2 monitors

Log in to a GNOME session

Open the control-center Display panel, e.g. by running

gnome-control-center display

Verify that the monitor on which the panel resides appears with a black bar in the panel

Drag the bar to the other monitor representation until it 'snaps over'

Observe that the panel moves to the other monitor

User Experience

The user experience (on supported hardware) will be defined by gnome-shell. If graphics hardware (and/or drivers) do not support gnome-shell, GNOME 3 starts in a 'fallback mode' where we run gnome-panel and metacity instead of gnome-shell. Note that this is not a 'GNOME 2' mode, the panel configuration will be adjusted to give a similar look-and-feel to the shell.

In GNOME 3, nautilus is no longer part of the desktop shell, but just a regular application, and it is no longer started by default.

Accessibility tools will work as well as (or hopefully better than) they used to. The onscreen keyboard will no longer be gok, but caribou, which may offer a slightly different user experience.

Dependencies

gnome-shell uses clutter, which relies on 3D hardware and drivers. In F13, the shell is known to work ok with Intel and ATI graphics, and work somewhat with the nouveau driver for NVidia graphics. For F14, we want the shell to work well with all three of

xorg-x11-drv-ati

xorg-x11-drv-intel

xorg-x11-drv-nouveau

Any packages that install modules for gtk2 (such as image loaders, input methods or theme engines) need to do extra work to make their functionality available to gtk3 too.

The libnotify 0.7.0 version removes some APIs that were available in 0.6. All packages that use libnotify to show notification bubbles and attach them to status icons will need some (minor) updates. (mostly done in rawhide)

The GDesktopAppInfoLookup extension mechanism has been disabled in GIO (it is still installed to mainain API stability, but GIO now determines default handlers by looking for x-scheme-handler mimetypes (see recent xdg-list discussion about this). Only very few packages in other GTK+-based desktops are affected by this.

To make default applications work, applications need to add suitable x-scheme-handler entries to the mimetype field in their desktop files. (mostly done in rawhide)

Contingency Plan

If gnome-shell is not complete or stable enough, keep it experimental and use the 'fallback mode'. If there are problems with certain combinations of graphics hardware and drivers, use gnome-shell only on known good combinations, and use
fallback mode everywhere else.

If the dbus-based accessibility stack is not sufficiently functional, we switch back to the CORBA-based stack.

Applications can be ported from GConf to dconf and from gtk2 to gtk3 one-by-one, so if the porting work is not complete (and it is very unlikely that it will be), we can just ship with some applications using the new technology, while others still use the old one.

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